1. Field of the Invention
The present invention relates to an ink jet recording device.
2. Description of Related Art
An ink jet recording device has a recording head in which a lot of nozzles axe arrayed. A recording medium (typically, recording sheet) on which an image is recorded is conveyed below the recording head. The recording head ejects ink drops from the nozzles at a predetermined timing while moving in a main scanning direction (a direction orthogonal to a recording sheet conveyance direction), thereby recording the image on the recording sheet. In recent years, the ink jet recording device has a function of recording the image on the recording sheet without forming a blank space in the border of the recording sheet as in photo printing. Thus, such image recording is called as “borderless recording”.
In the borderless recording, when an image is recorded, ink is ejected to the outside of the recording sheet beyond the border of the recording sheet as well as the recording sheet. For example, in the borderless recording at the front end and the rear end of the recording sheet, the recording sheet is positioned relative to the recording head so that some nozzles of the lot of nozzles may be located outside of the border of the recording sheet and eject ink drops on a platen disposed under the recording sheet. A groove extending in the main scanning direction is provided on an upper surface of the platen. The groove has an ink absorption therein. Thus, ink drops which are not adhered to the recording sheet are adsorbed in the ink absorption material. In Unexamined Patent Application Publication No. 2000-118058, in this manner, the image is recorded all over the recording sheet without forming a blank space in the border of the recording sheet and furthermore, a back surface of the recording sheet is prevented from being smeared with the ink ejected on the platen.
In these years, speeding-up of image recording by the ink jet recording device has been requested. To achieve speeding-up of image recording, upsizing of the recording head has been conventionally attempted. As the recording head is upsized, the number of nozzles aligned in the recording sheet conveyance direction is increased, thereby enabling high-speed recording. However, to perform the above-mentioned borderless recording satisfactorily, as the recording head is upsized, the width dimension (dimension in the recording sheet conveyance direction) of the groove formed on the platen need to be made larger.
When the above-mentioned borderless recording is performed, the recording sheet is disposed on the groove formed on the platen. Thus, when the width of the groove in the recording sheet conveyance direction is increased, the recording sheet is bent downward in the vertical direction and deformed to fall into the groove. When the recording sheet is bent, a distance between the nozzles of the recording head and the surface of the recording sheet is changed, thereby possibly causing defective recording.
In Unexamined Patent Application Publications No. 2001-80145 and No. 2002-307769, to eliminate such disadvantages, a sheet support member is provided in the groove on the platen so as to rotate in connection with conveyance of the recording sheet. Thus, the sheet support member supports the recording sheet advancing on the groove and a region of the sheet support member which supports the recording sheet moves in the groove width direction. Accordingly, even when the recording sheet is conveyed above the groove on the platen, the recording sheet is supported by the sheet support member.